gnu: python: Apply mips n32 fix to bundled libffi.

* gnu/packages/patches/python-libffi-mips-n32-fix.patch: New file.
* gnu/packages/python.scm (python-2, python): Add it.
* gnu-system.am (dist_patch_DATA): Add it.

gnu-system.am

@@ -316,6 +316,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/plotutils-libpng-jmpbuf.patch		\
   gnu/packages/patches/procps-make-3.82.patch			\
   gnu/packages/patches/python-fix-tests.patch			\
+  gnu/packages/patches/python-libffi-mips-n32-fix.patch		\
   gnu/packages/patches/qemu-make-4.0.patch			\
   gnu/packages/patches/qemu-multiple-smb-shares.patch		\
   gnu/packages/patches/qt4-tests.patch				\

gnu/packages/patches/python-libffi-mips-n32-fix.patch

@@ -0,0 +1,21 @@
+Fix handling of uint32_t arguments on the MIPS N32 ABI.
+
+Patch by Mark H Weaver <mhw@netris.org>.
+
+--- Modules/_ctypes/libffi/src/mips/ffi.c.orig	2013-03-16 07:19:39.000000000 -0400
++++ Modules/_ctypes/libffi/src/mips/ffi.c	2013-10-22 01:11:03.111985247 -0400
+@@ -170,7 +170,14 @@
+ 		break;
+ 		  
+ 	      case FFI_TYPE_UINT32:
++#ifdef FFI_MIPS_N32
++		/* The N32 ABI requires that 32-bit integers
++		   be sign-extended to 64-bits, regardless of
++		   whether they are signed or unsigned. */
++		*(ffi_arg *)argp = *(SINT32 *)(* p_argv);
++#else
+ 		*(ffi_arg *)argp = *(UINT32 *)(* p_argv);
++#endif
+ 		break;
+ 
+ 	      /* This can only happen with 64bit slots.  */

gnu/packages/python.scm

@@ -2,6 +2,7 @@
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013 Andreas Enge <andreas@enge.fr>
+;;; Copyright © 2014 Mark H Weaver <mhw@netris.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -50,6 +51,8 @@
       (method url-fetch)
       (uri (string-append "https://www.python.org/ftp/python/"
                           version "/Python-" version ".tar.xz"))
+      (patches (list (search-patch "python-libffi-mips-n32-fix.patch")))
+      (patch-flags '("-p0"))
       (sha256
        (base32
         "18gnpyh071dxa0rv3silrz92jw9qpblswzwv4gzqcwxzz20qxmhz"))))
@@ -190,7 +193,8 @@ data types.")
               (method url-fetch)
               (uri (string-append "https://www.python.org/ftp/python/"
                                   version "/Python-" version ".tar.xz"))
-              (patches (list (search-patch "python-fix-tests.patch")))
+              (patches (list (search-patch "python-fix-tests.patch")
+                             (search-patch "python-libffi-mips-n32-fix.patch")))
               (patch-flags '("-p0"))
               (sha256
                (base32